Objectives To determine the effect of ANH antagonist on renin-angiotensin-aldosterone system in Rhesus monkeys. We studied eight more male monkeys using the same protocol as reported last year and confirmed that ANH antagonist HS-142-1 leads to increased aldosterone and plasma renin activity levels leading to conclusion that ANH is a physiologic regulator of renin-angiotensin-aldosterone system. We also studied 6 female monkeys using a different antagonist A71915, but unfortunately, because of unstable level of anesthesia in these monkeys, we will probably not be able to reach any conclusions from this study. Keywords aldosterone, ANH, PRH, ANH antagonist